Mortal sin requires three conditions as the Catholic Catechism states:
1857 For a *sin *to be
mortal, three conditions must together be met: "Mortal sin is sin whose object is grave matter and which is also committed with full knowledge and deliberate consent."131
1858 Grave matter is specified by the Ten Commandments, corresponding to the answer of Jesus to the rich young man: "Do not kill, Do not commit adultery, Do not steal, Do not bear false witness, Do not defraud, Honor your father and your mother."132 The gravity of sins is more or less great: murder is graver than theft. One must also take into account who is wronged: violence against parents is in itself graver than violence against a stranger.
1859 Mortal sin requires
full knowledge and
complete consent. It presupposes knowledge of the sinful character of the act, of its opposition to God’s law. It also implies a consent sufficiently deliberate to be a personal choice. Feigned ignorance and hardness of heart133 do not diminish, but rather increase, the voluntary character of a sin.
1860 Unintentional ignorance can diminish or even remove the imputability of a grave offense. But no one is deemed to be ignorant of the principles of the moral law, which are written in the conscience of every man. The promptings of feelings and passions can also diminish the voluntary and free character of the offense, as can external pressures or pathological disorders. Sin committed through malice, by deliberate choice of evil, is the gravest.
Very often when we state something is a mortal sin, what we really mean is that it is “grave matter” and potentially mortal sin if the other two conditions for mortal sin are met. As Catholics, I think we have rather got into the bad habit of saying “It is a mortal sin” when what is correct is “It is grave matter and potentially mortal sin”. To state that another has committed a mortal sin is judgemental I think (for we are really saying all three conditions are present and that the person has chosen to damn their soul) but it is not at all meant to be so most often. Rather, what we actually mean is that something is grave matter and potentially mortal sin - hence a most serious matter indeed. We need to get into the habit of saying that grave matter is grave matter and not mortal sin unless it actually is and we know that the other two conditions are clearly present and this can only happen if the person concerned tells us that they were present. Of course, if someone shares with us that they had full knowledge and gave full consent to grave matter then we should inform them out of love, out of Charity, that what they have done sounds like mortal sin - and as YoungThinker has pointed out God calls us to honesty with each other and certainly to warn each other, if necessary and out of love for that other, that their soul sounds as if it is in dreadful peril and if a Catholic that they need to go to Confession as soon as possible urgently. And to pray for them.
TS
I think probably that this subject probably belongs in a Moral Theology forum.
